Shoemaking methods

ABSTRACT

A METHOD OF MAKING SHOES IN WHICH THE MARGIN OF A LASTED SHOE UPPER IS APPLIED TO MOLTEN THERMOPLASTIC ADHESIVE ON THE BOTTOM OF A LAST AND, AFTER THE ADHESIVE SETS TO FORM A LASTED SHOE UNIT, AND OUTSOLE MEMBER IS APPLIED.

Dec. 14, 1971 F. R. SMITH 3,626,532

SHOEMAKING METHODS Filed Aug. 31, 1970 2 Sheets-Sheot 1 Fl gl ln'uenior'F/"mk fRSmz'zh By his Aftor'ney 1971 F. R. SMITH SHOEMAKING mmnons 2Sheets-Sheet 2 Filed Aug. 31, 1970 United States Patent 3,626,532SHOEMAKIN G METHODS Frank R. Smith, Leicester, England, assignor to USMCorporation, Boston, Mass. Filed Aug. 31, 1970, Ser. No. 68,250 Claimspriority, application Great Britain, Sept. 5, 1969, 44,053/69 Int. Cl.A43d 21/00 US. Cl. 12-142 F 4 Claims ABSTRACT OF THE DISCLOSURE A methodof making shoes in which the margin of a lasted shoe upper is applied tomolten thermoplastic adhesive on the bottom of a last and, after theadhesive sets to form a lasted shoe unit, an outsole member is applied.

BACKGROUND OF THE INVENTION Of the various components which areassembled in the course of manufacture of a shoe, not the least costlyis the insole. The requirements of a satisfactory insole are that itshall be sufiiciently flexible in the forepart to allow for naturalbending of the foot at the ball region and yet be rigid enough towithstand the stresses of a lasting operation. The heel end of an insoleis not required to be flexible and generally must be rigid enough tosupport a stiffening component or shank piece and to receive the heelwhen attached to the shoe at a later stage in the manufacture. To meetthese requirements, some manufacturers have been using two-part insoles,the heel ends being of insole board and the forepart of a lightermaterial, flexible in the direction of the bending action of the foot.Whatever insole is used, however, certain difficulties arise inobtaining precise alignment of the insole with the edge of the lastbottom even if the insole is accurately cut to the correct size. Inpractice, the fit is often not quite accurate, and even slightinaccuracies of fit can mar the appearance of the feather line or bottomedge of the finished shoe above the outsole. Difficulties are alsoencountered where it is required to form an outsole directly on to thelasted shoe by a molding process, for example, by injection molding,since the mold cavity which is in the shape of the required outsole isenclosed partly by the underside of the lasted shoe, mold membersdefining the remainder of the cavity being in contact with the shoearound its feather line. Where this feather line is not uniform aroundthe shoe, the injected plastics material is likely to spue, thus marringthe finished shoe. Where the mold members include welt plates which buttagainst the feather line, these plates are liable to exert sufiicientpressure on the edges of the insole, particularly in the forepartregion, to cause it to bow away from the last bottom and where thepressures in the mold cavity are not sufiicient to iron out this bow,then the resulting shoe will be faulty.

The invention provides, among its several features, a method of lastingshoes comprising the steps of positioning an upper about a last;applying thermoplastic adhesive to marginal portions of the last bottom;forming a lasted unit by laying the margin of the upper against saidmarginal portions of the last bottom to which the adhesive is applied,said adhesive acting to consolidate the marginal portions of the upperin a wiped condition; and providing the lasted unit with an outsolemember, the arrangement being such that any adhesion of the marginalportions of the upper to the last bottom is impermanent.

In most types of shoes the provision of a shank member is needed to givethe required rigidity to the shank and heel end regions of the shoebottom. In a shoe which has been lasted in the forepart region using amethod according to the present invention, the shank member 3,625,532Patented Dec. 14, 1971 "ice may be incorporated by being secured to apart-insole which does not extend into the forepart region of the shoebut provides support for the shank member in the shank and heel endregions. Where such a part-insole is provided, it may be foundconvenient to last the shoe by a conventional cement lasting process inthe shank and heel end regions whereby the margin of the upper in thoseregions is secured to marginal portions of the partinsole. The partiallylasted shoe may then be subjected to a forepart lasting operation usinga method according to the present invention. An outsole member in theform of a preformed shoe bottom unit may then be secured by means ofadhesive to the bottom of the lasted unit, the wiped margins having beenroughed in the usual way. If it isrequired to provide an outsole memberby molding plastics material on to the bottom of the lasted unit, theshank may be positioned within the mold cavity by suitable means.

There will now be given, with reference to the accompanying drawings, adetailed description of a method, illustrative of the invention, ofmaking a shoe having a part-insole extending over the waist and heel endregions of said shoe. It will be understood that the illustrative methodis selected for description merely by Way of exemplification of theinvention and not by way of limitation thereof.

In the accompanying drawings:

FIG. 1 is a view of the underside of an unfinished shoe which has beenconstructed according to the illustrative method;

FIG. 2 is a diagrammatic view of a step in the illustrative method;

FIG. 3 is a section taken on line III-III of FIG. 1;

FIG. 4 is an enlarged view of a portion of FIG. 3, and

FIG. 5 shows a section through a completed shoe.

A part-insole 2 bearing a shank member 4 is positioned on a last 6 sothat a metal plate 8 secured to the bottom of the last is covered by thepart-insole in the shank and heel end regions of the last bottom and isexposed in the forepart region. The last may be formed of wood orplastic material with a metal bottom plate extending at least overthemarginal portions of the last bottom in the regions where there is noinsole. Where an outsole member is to be directly molded on to the shoe,the last may be a metal foot form. An upper 10 is placed around the lastso that marginal portions of the upper project beyond the last bottom inthe shank and heel end regions and the shoe is then lasted in thoseregions by well-known operations. The heel seat lasting operation can beperformed on a conventional tack seat lasting machine, and the shanklasting can be accomplished on any suitable machine. A combined heelseat and shank lasting operation, if preferred, may be performed onmachines commonly available for this purpose.

The forepart of the upper is then positioned for lasting as shown inFIG. 2. The lasting operation may be carried out on any suitableforepart lasting machine. In such machines, grippers, diagrammaticallyrepresented at 12, grasp the marginal portions of the upper and pull theupper taut about the last. A continuous bead of molten adhesive 14 isthen applied to marginal portions of the forepart of the last bottom.The marginal portions of the upper are then wiped by wiping means (notshown) against the last bottom and the still molten adhesive flowsbetween the folds and pleats of the marginal portions of the upperbefore it sets in a firm band which adheres to the marginal portions ofthe upper, thus consolidating them in the wiped condition. The adhesive,which is applied to the last bottom in order to consolidate the upper,may be one which is capable, while molten, of

flowing between the folds and pleats of the lasted marginal portions ofthe upper but will quickly set to consolidate the marginal portionsfirmly in the wiped condition. One type of adhesive which may be used isa polyester cement which has the added advantage that no release agentis required to be applied to the metal last bottom to prevent adhesionof the cement thereto. Where adhesion to an extent which will hinderslipping the last from the completed shoe is likely, because of the typeof adhesive used or of the material of the last bottom, then a suitablerelease agent will be required.

If required to enhance the bond with an outsole unit, the lastedmarginal portions of the upper may be roughed by any conventionalroughing machine and would then have the appearance shown in FIG. 1. Theshoe is then ready to receive an outsole member 18. Where the outsolemember is to be molded on to the shoe, an interlayer '16 may be placedon the exposed last bottom to prevent adhesion of the injected plasticsmaterial to the last bottom. Molding takes place in a conventionalmanner and the last is then slipped from the shoe. FIG. 5 shows thefinished shoe before insertion of a suitable lining. It can be seen thatthe inside surface of the shoe bottom is substantially smooth and even,requiring only a lining such as an insock to complete the shoe which byits construction is particularly flexible in wear.

It will be seen in FIG. 2 that the upper 10 can be provided with a toereinforcement which may be of thermoplastic material. The edge of thereinforcement which is visible in that figure will be wiped in as partof the marginal portions of the upper during the forepart lastingoperation. Because the reinforcement is in a flaccid condition asrequired during this operation, it will fold and pleat with the marginalportions of the upper as they are wiped in. On cooling, thereinforcement returns to a relatively rigid state and generally enhancesthe consolidation effect of the bead 14 of adhesive at the extreme toeend of the shoe.

The part-insole 2 shown in FIGS. 1, 2 and 5 may be specially constructedas a multi-layered assembly, the shank member being sandwiched betweentwo layers thereof. It will be especially convenient if at least thelower layer, i.e., that furthest from the last bottom when assembled, isof a material which well receives a cement lasting operation. The upperlayer may conveniently be of insole board material. It should beapparent that the part-insole could be omitted entirely and the heel andshank portions of the shoe could be lasted and consolidated beforeoutsole attachment by adhesive alone in the same manner as the forepartregion. If shank reinforcement is desired, a shank member may besupported by a spider of plastics material or be temporarily secured tothe last bottom by other means. Alternatively, a shank member can bepositioned in a mold cavity where the outsole unit is to be injectionmolded directly onto the consolidated upper.

Having thus described my invention, what I claim as novel and desire tosecure by Letters Patent of the United States is:

1. A method of making shoes including the steps of:

assembling an upper On a last;

applying molten thermoplastic adhesive to marginal portions of the lastbottom;

shaping the upper about the last and laying the margin of the upperinwardly over the last bottom on said molten adhesive;

allowing the adhesive to set to hold the upper in consolidated shapedcondition to form a lasted shoe unit, and

applying an outsole member to the bottom of the shoe unit.

2. A method according to claim 1 in which said adhesive is applied tothe forepart of the last bottom and the heelward portion of the uppermargin is secured to a part-insole placed on the heelward portion of thelast bottom.

3. A method according to claim 1 in which the step of applying theoutsole member includes forming said member by injection moldingdirectly on the bottom of the lasted shoe unit.

4. A method according to claim 1 having the addi- References CitedUNITED STATES PATENTS 2/1958 Stritter 12-142 F 12/1960 Stix 12-145PATRICK D. LAWSON, Primary Examiner US. Cl. X.R. 12145

